/* gzlib.c -- zlib functions common to reading and writing gzip files
 * Copyright (C) 2004-2019 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

#include "gzguts.h"

#if defined(_WIN32) && !defined(__BORLANDC__)
#define LSEEK lseek
#else
#if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE - 0
#define LSEEK lseek64
#else
#define LSEEK lseek
#endif
#endif

/* Local functions */
local void gz_reset OF((gz_statep));
local gzFile gz_open OF((const void*, int, const char*));

#if defined UNDER_CE

/* Map the Windows error number in ERROR to a locale-dependent error message
   string and return a pointer to it.  Typically, the values for ERROR come
   from GetLastError.

   The string pointed to shall not be modified by the application, but may be
   overwritten by a subsequent call to gz_strwinerror

   The gz_strwinerror function does not change the current setting of
   GetLastError. */
char ZLIB_INTERNAL* gz_strwinerror(error)
DWORD error;
{
  static char buf[1024];

  wchar_t* msgbuf;
  DWORD lasterr = GetLastError();
  DWORD chars =
      FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER,
                    NULL, error, 0, /* Default language */
                    (LPVOID)&msgbuf, 0, NULL);
  if (chars != 0) {
    /* If there is an \r\n appended, zap it.  */
    if (chars >= 2 && msgbuf[chars - 2] == '\r' && msgbuf[chars - 1] == '\n') {
      chars -= 2;
      msgbuf[chars] = 0;
    }

    if (chars > sizeof(buf) - 1) {
      chars = sizeof(buf) - 1;
      msgbuf[chars] = 0;
    }

    wcstombs(buf, msgbuf, chars + 1);
    LocalFree(msgbuf);
  } else {
    sprintf(buf, "unknown win32 error (%ld)", error);
  }

  SetLastError(lasterr);
  return buf;
}

#endif /* UNDER_CE */

/* Reset gzip file state */
local void gz_reset(state) gz_statep state;
{
  printk("gz_reset.\n");
  state->x.have = 0;            /* no output data available */
  if (state->mode == GZ_READ) { /* for reading ... */
    state->eof = 0;             /* not at end of file */
    state->past = 0;            /* have not read past end yet */
    state->how = LOOK;          /* look for gzip header */
  } else                        /* for writing ... */
    state->reset = 0;           /* no deflateReset pending */
  state->seek = 0;              /* no seek request pending */
  gz_error(state, Z_OK, NULL);  /* clear error */
  state->x.pos = 0;             /* no uncompressed data yet */
  state->strm.avail_in = 0;     /* no input data yet */
}

/* Open a gzip file either by name or file descriptor. */
local gzFile gz_open(path, fd, mode) const void* path;
int fd;
const char* mode;
{
  gz_statep state;
  z_size_t len;
  int oflag;

  /* check input */
  if (path == NULL)
    return NULL;

  /* allocate gzFile structure to return */
  state = (gz_statep)malloc(sizeof(gz_state));
  if (state == NULL)
    return NULL;
  state->size = 0;         /* no buffers allocated yet */
  state->want = GZBUFSIZE; /* requested buffer size */
  state->msg = NULL;       /* no error message yet */

  /* interpret mode */
  state->mode = GZ_NONE;
  state->level = Z_DEFAULT_COMPRESSION;
  state->strategy = Z_DEFAULT_STRATEGY;
  state->direct = 0;
  printk("1\n");
  while (*mode) {
    if (*mode >= '0' && *mode <= '9')
      state->level = *mode - '0';
    else
      switch (*mode) {
        case 'r':
          state->mode = GZ_READ;
          break;
#ifndef NO_GZCOMPRESS
        case 'w':
          state->mode = GZ_WRITE;
          break;
        case 'a':
          state->mode = GZ_APPEND;
          break;
#endif
        case '+': /* can't read and write at the same time */
          free(state);
          return NULL;
        case 'b': /* ignore -- will request binary anyway */
          break;
#ifdef O_CLOEXEC
        case 'e':
          cloexec = 1;
          break;
#endif
#ifdef O_EXCL
        case 'x':
          exclusive = 1;
          break;
#endif
        case 'f':
          state->strategy = Z_FILTERED;
          break;
        case 'h':
          state->strategy = Z_HUFFMAN_ONLY;
          break;
        case 'R':
          state->strategy = Z_RLE;
          break;
        case 'F':
          state->strategy = Z_FIXED;
          break;
        case 'T':
          state->direct = 1;
          break;
        default: /* could consider as an error, but just ignore */
            ;
      }
    mode++;
  }
  printk("2\n");
  /* must provide an "r", "w", or "a" */
  if (state->mode == GZ_NONE) {
    free(state);
    return NULL;
  }

  /* can't force transparent read */
  if (state->mode == GZ_READ) {
    if (state->direct) {
      free(state);
      return NULL;
    }
    state->direct = 1; /* for empty file */
  }

  /* save the path name for error messages */
  len = strlen((const char*)path);
  state->path = (char*)malloc(len + 1);
  if (state->path == NULL) {
    free(state);
    return NULL;
  }
#if !defined(NO_snprintf) && !defined(NO_vsnprintf)
  (void)snprintf(state->path, len + 1, "%s", (const char*)path);
  printk("3\n");
#else
  strcpy(state->path, path);
#endif

  /* compute the flags for open() */
  oflag =
#ifdef O_LARGEFILE
      O_LARGEFILE |
#endif
#ifdef O_BINARY
      O_BINARY |
#endif
#ifdef O_CLOEXEC
      (cloexec ? O_CLOEXEC : 0) |
#endif
      (state->mode == GZ_READ
           ? O_RDONLY
           : (O_WRONLY | O_CREAT |
#ifdef O_EXCL
              (exclusive ? O_EXCL : 0) |
#endif
              (state->mode == GZ_WRITE ? O_TRUNC : O_APPEND)));

  /* open the file with the appropriate flags (or just use fd) */
  state->fd = fd > -1 ? fd : (open((const char*)path, oflag, 0666));
  printk("4\n");
  if (state->fd == -1) {
    free(state->path);
    free(state);
    return NULL;
  }
  if (state->mode == GZ_APPEND) {
    LSEEK(state->fd, 0, SEEK_END); /* so gzoffset() is correct */
    state->mode = GZ_WRITE;        /* simplify later checks */
  }

  /* save the current position for rewinding (only if reading) */
  if (state->mode == GZ_READ) {
    state->start = LSEEK(state->fd, 0, SEEK_CUR);
    if (state->start == -1)
      state->start = 0;
  }
  printk("5\n");
  /* initialize stream */
  gz_reset(state);
  printk("6\n");
  /* return stream */
  return (gzFile)state;
}

/* -- see zlib.h -- */
gzFile ZEXPORT gzopen(path, mode) const char* path;
const char* mode;
{
  printk("GZOPEN.\n");
  return gz_open(path, -1, mode);
}

/* -- see zlib.h -- */
gzFile ZEXPORT gzopen64(path, mode) const char* path;
const char* mode;
{ return gz_open(path, -1, mode); }

/* -- see zlib.h -- */
gzFile ZEXPORT gzdopen(fd, mode)
int fd;
const char* mode;
{
  char* path; /* identifier for error messages */
  gzFile gz;

  if (fd == -1 || (path = (char*)malloc(7 + 3 * sizeof(int))) == NULL)
    return NULL;
#if !defined(NO_snprintf) && !defined(NO_vsnprintf)
  (void)snprintf(path, 7 + 3 * sizeof(int), "<fd:%d>", fd);
#else
  sprintf(path, "<fd:%d>", fd); /* for debugging */
#endif
  gz = gz_open(path, fd, mode);
  free(path);
  return gz;
}

/* -- see zlib.h -- */
#ifdef WIDECHAR
gzFile ZEXPORT gzopen_w(path, mode) const wchar_t* path;
const char* mode;
{ return gz_open(path, -2, mode); }
#endif

/* -- see zlib.h -- */
int ZEXPORT gzbuffer(file, size)
gzFile file;
unsigned size;
{
  gz_statep state;

  /* get internal structure and check integrity */
  if (file == NULL)
    return -1;
  state = (gz_statep)file;
  if (state->mode != GZ_READ && state->mode != GZ_WRITE)
    return -1;

  /* make sure we haven't already allocated memory */
  if (state->size != 0)
    return -1;

  /* check and set requested size */
  if ((size << 1) < size)
    return -1; /* need to be able to double it */
  if (size < 2)
    size = 2; /* need two bytes to check magic header */
  state->want = size;
  return 0;
}

/* -- see zlib.h -- */
int ZEXPORT gzrewind(file)
gzFile file;
{
  gz_statep state;

  /* get internal structure */
  if (file == NULL)
    return -1;
  state = (gz_statep)file;

  /* check that we're reading and that there's no error */
  if (state->mode != GZ_READ ||
      (state->err != Z_OK && state->err != Z_BUF_ERROR))
    return -1;

  /* back up and start over */
  if (LSEEK(state->fd, state->start, SEEK_SET) == -1)
    return -1;
  gz_reset(state);
  return 0;
}

/* -- see zlib.h -- */
z_off64_t ZEXPORT gzseek64(file, offset, whence)
gzFile file;
z_off64_t offset;
int whence;
{
  unsigned n;
  z_off64_t ret;
  gz_statep state;

  /* get internal structure and check integrity */
  if (file == NULL)
    return -1;
  state = (gz_statep)file;
  if (state->mode != GZ_READ && state->mode != GZ_WRITE)
    return -1;

  /* check that there's no error */
  if (state->err != Z_OK && state->err != Z_BUF_ERROR)
    return -1;

  /* can only seek from start or relative to current position */
  if (whence != SEEK_SET && whence != SEEK_CUR)
    return -1;

  /* normalize offset to a SEEK_CUR specification */
  if (whence == SEEK_SET)
    offset -= state->x.pos;
  else if (state->seek)
    offset += state->skip;
  state->seek = 0;

  /* if within raw area while reading, just go there */
  if (state->mode == GZ_READ && state->how == COPY &&
      state->x.pos + offset >= 0) {
    ret = LSEEK(state->fd, offset - (z_off64_t)state->x.have, SEEK_CUR);
    if (ret == -1)
      return -1;
    state->x.have = 0;
    state->eof = 0;
    state->past = 0;
    state->seek = 0;
    gz_error(state, Z_OK, NULL);
    state->strm.avail_in = 0;
    state->x.pos += offset;
    return state->x.pos;
  }

  /* calculate skip amount, rewinding if needed for back seek when reading */
  if (offset < 0) {
    if (state->mode != GZ_READ) /* writing -- can't go backwards */
      return -1;
    offset += state->x.pos;
    if (offset < 0) /* before start of file! */
      return -1;
    if (gzrewind(file) == -1) /* rewind, then skip to offset */
      return -1;
  }

  /* if reading, skip what's in output buffer (one less gzgetc() check) */
  if (state->mode == GZ_READ) {
    n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > offset
            ? (unsigned)offset
            : state->x.have;
    state->x.have -= n;
    state->x.next += n;
    state->x.pos += n;
    offset -= n;
  }

  /* request skip (if not zero) */
  if (offset) {
    state->seek = 1;
    state->skip = offset;
  }
  return state->x.pos + offset;
}

/* -- see zlib.h -- */
z_off_t ZEXPORT gzseek(file, offset, whence)
gzFile file;
z_off_t offset;
int whence;
{
  z_off64_t ret;

  ret = gzseek64(file, (z_off64_t)offset, whence);
  return ret == (z_off_t)ret ? (z_off_t)ret : -1;
}

/* -- see zlib.h -- */
z_off64_t ZEXPORT gztell64(file)
gzFile file;
{
  gz_statep state;

  /* get internal structure and check integrity */
  if (file == NULL)
    return -1;
  state = (gz_statep)file;
  if (state->mode != GZ_READ && state->mode != GZ_WRITE)
    return -1;

  /* return position */
  return state->x.pos + (state->seek ? state->skip : 0);
}

/* -- see zlib.h -- */
z_off_t ZEXPORT gztell(file)
gzFile file;
{
  z_off64_t ret;

  ret = gztell64(file);
  return ret == (z_off_t)ret ? (z_off_t)ret : -1;
}

/* -- see zlib.h -- */
z_off64_t ZEXPORT gzoffset64(file)
gzFile file;
{
  z_off64_t offset;
  gz_statep state;

  /* get internal structure and check integrity */
  if (file == NULL)
    return -1;
  state = (gz_statep)file;
  if (state->mode != GZ_READ && state->mode != GZ_WRITE)
    return -1;

  /* compute and return effective offset in file */
  offset = LSEEK(state->fd, 0, SEEK_CUR);
  if (offset == -1)
    return -1;
  if (state->mode == GZ_READ)       /* reading */
    offset -= state->strm.avail_in; /* don't count buffered input */
  return offset;
}

/* -- see zlib.h -- */
z_off_t ZEXPORT gzoffset(file)
gzFile file;
{
  z_off64_t ret;

  ret = gzoffset64(file);
  return ret == (z_off_t)ret ? (z_off_t)ret : -1;
}

/* -- see zlib.h -- */
int ZEXPORT gzeof(file)
gzFile file;
{
  gz_statep state;

  /* get internal structure and check integrity */
  if (file == NULL)
    return 0;
  state = (gz_statep)file;
  if (state->mode != GZ_READ && state->mode != GZ_WRITE)
    return 0;

  /* return end-of-file state */
  return state->mode == GZ_READ ? state->past : 0;
}

/* -- see zlib.h -- */
const char* ZEXPORT gzerror(file, errnum)
gzFile file;
int* errnum;
{
  gz_statep state;

  /* get internal structure and check integrity */
  if (file == NULL)
    return NULL;
  state = (gz_statep)file;
  if (state->mode != GZ_READ && state->mode != GZ_WRITE)
    return NULL;

  /* return error information */
  if (errnum != NULL)
    *errnum = state->err;
  return state->err == Z_MEM_ERROR ? "out of memory"
                                   : (state->msg == NULL ? "" : state->msg);
}

/* -- see zlib.h -- */
void ZEXPORT gzclearerr(file)
gzFile file;
{
  gz_statep state;

  /* get internal structure and check integrity */
  if (file == NULL)
    return;
  state = (gz_statep)file;
  if (state->mode != GZ_READ && state->mode != GZ_WRITE)
    return;

  /* clear error and end-of-file */
  if (state->mode == GZ_READ) {
    state->eof = 0;
    state->past = 0;
  }
  gz_error(state, Z_OK, NULL);
}

/* Create an error message in allocated memory and set state->err and
   state->msg accordingly.  Free any previous error message already there.  Do
   not try to free or allocate space if the error is Z_MEM_ERROR (out of
   memory).  Simply save the error message as a static string.  If there is an
   allocation failure constructing the error message, then convert the error to
   out of memory. */
void ZLIB_INTERNAL gz_error(state, err, msg)
gz_statep state;
int err;
const char* msg;
{
  /* free previously allocated message and clear */
  if (state->msg != NULL) {
    if (state->err != Z_MEM_ERROR)
      free(state->msg);
    state->msg = NULL;
  }

  /* if fatal, set state->x.have to 0 so that the gzgetc() macro fails */
  if (err != Z_OK && err != Z_BUF_ERROR)
    state->x.have = 0;

  /* set error code, and if no message, then done */
  state->err = err;
  if (msg == NULL)
    return;

  /* for an out of memory error, return literal string when requested */
  if (err == Z_MEM_ERROR)
    return;

  /* construct error message with path */
  if ((state->msg = (char*)malloc(strlen(state->path) + strlen(msg) + 3)) ==
      NULL) {
    state->err = Z_MEM_ERROR;
    return;
  }
#if !defined(NO_snprintf) && !defined(NO_vsnprintf)
  (void)snprintf(state->msg, strlen(state->path) + strlen(msg) + 3, "%s%s%s",
                 state->path, ": ", msg);
#else
  strcpy(state->msg, state->path);
  strcat(state->msg, ": ");
  strcat(state->msg, msg);
#endif
}

#ifndef INT_MAX
/* portably return maximum value for an int (when limits.h presumed not
   available) -- we need to do this to cover cases where 2's complement not
   used, since C standard permits 1's complement and sign-bit representations,
   otherwise we could just use ((unsigned)-1) >> 1 */
unsigned ZLIB_INTERNAL gz_intmax() {
  unsigned p, q;

  p = 1;
  do {
    q = p;
    p <<= 1;
    p++;
  } while (p > q);
  return q >> 1;
}
#endif
